choosing the Right LED Power Supply: A Comprehensive Guide by MIJI LED

LED lighting products come in various types, and most of them require an LED power supply, also known as an LED transformer or driver. It’s crucial to understand the different LED products and the types of power supplies they require.

You also need to be aware of their installation constraints to ensure compatibility between your lights and their transformers.

Remember, using the wrong LED power supply can damage your LED lights.

In this article, we’ll guide you on how to select the right power supply for your lighting project and how to install it. If you encounter any issues with your LED power supply, this guide can help you with standard troubleshooting.


Why do you need an LED power supply? 

Most LED light strips operate at low voltages of 12Vdc or 24Vdc. Connecting LED light strips directly to mains electricity at 110Vac or 220Vac can damage them. Therefore, we need an LED power supply, also known as an LED transformer, to convert mains electricity into the corresponding voltage required for LED light strips, such as 12Vdc or 24Vdc.

Factors to consider Finding the right LED power supply for LED light strips is not straightforward. Selecting the most suitable LED power supply involves considering various factors and understanding some basic knowledge about LED power supplies.

Constant Voltage or Constant Current LED Power Supply?

 What is Constant Voltage LED Power Supply? Constant voltage LED drivers typically have fixed voltage ratings of 5V, 12V, or 24V or other voltage ratings with a certain current or maximum current range. All LED light strips must use constant voltage power supplies.

What is Constant Current LED Power Supply? Constant current LED drivers will have similar ratings but with fixed ampere (A) or milliampere (mA) values, with a certain voltage range or maximum voltage. LED light strips generally cannot use constant current power supplies because the current is fixed, and cutting or connecting LED light strips can change the current.

Wattage You need to know how many watts the LED lights will consume. If you want to run multiple lights with one power supply, you must add up the wattage to find the total wattage used. Ensure you have a sufficiently large power supply by adding 20% buffer to the total power calculated from the LEDs. This can be quickly done by multiplying the total power by 1.2 and then finding a power supply rated for that power.

For example, if you have two rolls of LED light strips, each 5 meters long, with a power of 14.4W/m, then the total power is 14.4 * 5 * 2 = 144W. So, the minimum wattage of the power supply you need is 144 * 1.2 = 172.8W.

Voltage You need to ensure that the input and output voltage of your LED power supply are correct. Input Voltage The input voltage depends on the country where the power supply is used.

The power supply voltage varies from country to country. For example, China uses 220Vac (50Hz), and the USA uses 120Vac (50Hz). But some LED power supplies have a full voltage range input, meaning they can be used in any country globally.

Country Voltage

Output Voltage The output voltage needs to match the voltage of your LED light strips.

If the output voltage exceeds the LED light strip’s voltage, it can damage the LED light strip and potentially cause a fire.

Dimmability All our LED light strips are PWM dimmable. If you need to adjust their brightness, you must ensure that your power supply has dimming capability. The datasheet of the power supply will indicate whether it is dimmable and what type of dimming control to use.

Common dimming methods include:

0/1-10V dimming

TRIAC dimming

DALI dimming

DMX512 dimming

Temperature Resistance and Waterproofing One important factor to consider when choosing a power supply is the area of use and the operating environment. The power supply operates most efficiently within its temperature parameter range. The power supply specifications should include a safe operating temperature range. It’s best to operate within this range and ensure it’s not placed in a location that generates heat and exceeds the maximum operating temperature. Placing the power supply in an enclosed space without a ventilation system is generally a bad idea. This will allow even the smallest heat sources to accumulate over time, eventually reaching cooking levels. Therefore, make sure the area is not too hot or too cold, and heat does not accumulate to destructive levels.

Every LED power supply is labeled with an IP rating.

The IP rating or Ingress Protection rating is a number assigned to LED drivers to indicate their level of protection against solid objects and liquids. The rating is usually represented by two numbers, with the first indicating protection against solid objects and the second indicating protection against liquids. For example, an IP68 rating means the device is fully protected against dust ingress and can be submerged in water up to 1.5 meters deep for 30 minutes.

If you need to use an LED power supply in an outdoor area exposed to rain, choose one with an appropriate IP rating.

Efficiency  Another key feature to consider when selecting an LED driver is efficiency. Efficiency, expressed as a percentage, tells you how much input power the driver can use to power the LEDs. Typical efficiency ranges from 80-85%, but UL Class 1 drivers, which can operate more LEDs, usually have higher efficiency.

Power Factor The rated power factor is the ratio of actual power (watts) used by the load to the apparent power (voltage x current) entering the circuit: Power Factor = Watts / (Volts x Amps). The power factor value is calculated by dividing actual power by apparent value.

The power factor range is between -1 and 1. The closer the power factor is to 1, the higher the efficiency of the driver.

Size When selecting a power supply for your LED project, you need to know where it needs to be installed. If you want to fit it into a product you’re making, it must be small enough to fit the space provided. If it’s outside the application, there should be a way to install it nearby. There are various sizes and shapes of power supplies available to meet your needs.

Class I or II LED Drivers Class I LED drivers have basic insulation and must include protective earth connection to reduce the risk of electric shock. Their safety is achieved by using basic insulation. It also provides a way to connect protective earth conductors to the building in case the basic insulation fails, which would otherwise produce hazardous voltages.

Class II LED drivers not only rely on basic insulation to prevent electric shock but also must provide additional safety measures such as double insulation or reinforced insulation. It does not depend on protective earth or installation conditions.

Safety Protection Features For safety reasons, LED power supplies should have protection functions such as overcurrent, over-temperature, short circuit, open circuit, etc. These safety measures result in the incorrect shutdown of the power supply. These protection functions are not mandatory. However, if you want to use it safely in case of problems, you should only install power supplies with these protection functions.

UL Listing Certification Having a UL-certified LED power supply means better safety and better quality.

Additionally, some projects require LED power supplies to be UL certified.